The appearance of roofplasties on lateral hyperextension radiographs

Graft impingement by the roof of the intercondylar notch has recently been implicated as a cause of failure after anterior cruciate ligament reconstruction. Posterior tibial tunnel placement and roofplasties have been advocated to reduce the incidence of graft-roof impingement. Based on our earlier work in this area, we were concerned that lateral hyperextension radiographs, as advocated by Howell and associates to evaluate impingement, did not accurately reflect the extent of roofplasty accomplished intraoperatively. We hypothesized that these radiographs suggested that the grafts were moderately impinged, when, in fact, they were impingement-free. In a cadaver model, we compared radiographs made before and after roofplasty to determine whether there were any resultant changes in the appearance of the intercondylar roof. We found no detectable difference in 70% (14 of 20) of specimens. A second, subtle line superior to the intercondylar line appeared on radiographs in 30% of the specimens. We concluded that postoperative lateral radiographs may fail to show the effect of a roofplasty and can lead to the overdiagnosis of graft-roof impingement.